Condenser and exhaust conduit therefor



Nmn E, W W F. c. BARBER 2,486,??5

CONDENSER AND EXHAUST GONDUIT THEREFOR Filed Aug. 12,. 1946 L INVENTOR FEST c. BARBER FIG. :1, u

Patented Nov. 1, 1949 UNITED STATES PATENT OFFICE CONDENSER AND EXHAUST CONDUIT THEREFOR 2 Claims.

This invention relates to apparatus for use in smelting. The invention also relates to a smelting process. One embodiment of my invention relates to apparatus used in smelting zinc. In certain respects the apparatus of the present invention relates to an improvement of, and a refinement over, the various pieces of apparatus described and claimed in my Patents 2,191,066, granted February 20, 1940, and 2,206,150, granted July 2, 1940, and the smelting process-is an improvement over the smelting process described in these patents,

In the smelting of zinc to produce the metal in an uncombined form zinc oxide and coke, in a finely divided or pulverized form, are intimately mixed and heated together. A chemical reaction takes place involving these materials and zinc is released as a free metal. There is also copious production of carbon monoxide, which either passes off with the efiluent gas or, as is presently more often the case, burns as the efliuent gas leaves the condenser in which the zinc is recovered.

In commercial practice this chemical reaction, or smelting, is often carried out in a relatively small retort, which is frequently a circular or elliptical cylinder about one foot in diameter and about six feet long and closed at one end. This cylinder has walls about an inch thick which are composed of baked clay. or other ceramic material, which is quite resistant to high temperatures and the destructive action of hot corrosive materials, such as molten or vaporized metals. This retort is placed in a furnace with its long axis substantially horizontal, the closed end being within the furnace and the open end being at the edge of the furnace and substantially flush with the outer wall thereof. This outer, open end is preferably slightly lower than the inner, closed end so that any liquid material such as molten metal which may at any time be within the retort will tend to flow out of the retort and yet any solid material such as unreacted zinc oxide, or coke, or cinders, or the like, which remain after reaction, will not tend to slide out of the retort by the force of gravity.

As a result of the high temperatures which exist within this retort, the zinc or other metal produced by the smelting of the material therein will be at or near its boiling point and therefore will have an appreciable vapor pressure and substantial amounts, if not all, of the zinc will exist in the vapor state. In order to be collected the metal vapor must be condensed, much as the vapor of any other material which it is desired to recover, and for this purpose a condenser is used in cooperation with the aforementioned retort. This condenser is made of a temperature-resistant ceramic material which is similar to or the same as the material from which the retort is made. In one form, this condenser has the shape of a hollow, truncated cone about two and onehalf feet long, with walls which are also about an inch thick. The base or larger end of this condenser has essentially the same dimensions as the open end of the aforementioned retort, against which it is fitted more or less snugly. The smaller end of this conical condenser is between about two and about six inches in diameter. The condenser rests upon brackets or the like, with its axis also substantially horizontal, but with enough of an angle therefrom that the bottom portion of the smaller end is slightly lower than the bottom portion of the larger end. Free metal in a substantially molten state collects in this condenser, running into it from the retort and condensing from the gases and vapors which leave the retort and pass into and through the interior of the condenser toward the smaller end thereof. Usually there are numerous long, horizontal rows of these retorts and condensers, one row directly above another, up to about the height of a mans head, with several hundred being heated in a single, long furnace.

Prior to the invention of the apparatus described in my Patents 2,191,066 and 2,206,150, previously mentioned, and in many places today where such apparatus is not used, it is the practice of the art partially to close or dam the small end of this condenser with a handful, more or less, of dampened granular material such as cinders or the like, leaving a small hole or unclosed portion near the top part of the condenser through which pass gaseous reaction products of the smelting operation, somewhat cooled in the condenser and freed of substantially all of the metal vapors, excepting small amounts of finely divided particles of metal or of metal oxide. This handful of material must of necessity be put in place by hand, and whenever it is desired to draw off the molten metal which has collected in the condenser, this dam must be removed completely. In doing this, the dam material and molten metal are raked or scraped into a ladle, the dam material floating on top of the metal and being removed from time to time as collection of metal from large numbers of individual retorts proceeds.

In my previously mentioned patents are disclosed various apparatus serving as closures suitable for use in such smelting operations. In the usual use of such a closure a minor portion, about 1 to about 3 per cent, of the metal originally present in the metal compound introduced into the retort often escapes from the condenser along with the carbon monoxide and other gases escaping therefrom, generally in the form of fine, suspended particles of metal or metal oxide. I have now invented an apparatus, and a procedure, wh reby the m01ten metal is held in the condenser and such finely divided metal-comprising particles are collected and recovered. The use of one specific embodiment of my invention also results in utilization, as fuel for heating the furnaces, of carbon monoxide contained in the effiuent gas.

An object of my invention is to provide means for recovering zinc.

Another object of my invention is to recover metal from a smelter.

Still another object of my invention is to put to a useful purpose carbon monoxide produced in the smelting of a metal oxide.

Further objects of my invention are to recover both liquid metal and finely divided solid metal, and/or metal oxide, from a smelter, and to provide apparatus for such a purpose.

Further objects and advantages of m invention will now become apparent, to one skilled in the art, from the accompanying disclosure and discussion.

Various specific embodiments of my invention will now be described in connection with the accompanying drawings, which form a part of this specification. Figure 1 shows, diagrammatically, a front view of a partial section of a smelting furnace, illustrating apparatus for practicing an embodiment of my invention Figure 2 is a side view, partly in section, of a part of the apparatus shown in Figure 1, taken on the line 2-2 and looking in the direction of the arrows. Figure 3 is a top view of the embodiment illustrated in Figures 1 and. 2.

Figure 4 is a top plan view of another specific embodiment of my invention, differing in some specific respects from the embodiment shown in Figures 1 to 3. Figure 5 is a side plan view of the same embodiment shown in Figure 4.

It will be readily appreciated that each of the figures is diagrammatic, and is illustrative and not drawn to scale. Individual items which are the same, or perform the same functions, in the several figures are identified with the same reference numerals.

Referring now to Figures 1 to 3, a condenser body Iil is in a substantially horizontal position, and is supported as has been discussed, by means not shown. The open end is closed with a cover II, and gases formed by the chemical reactions of the smelting escape through a vent hole 23, which may be a notch at the small end of the condenser, as shown in Fig. 3. These gases pass through a small covering hood 20 to a gathering exhaust conduit I2. This exhaust conduit is a horizontal branch of an exhaust system, being joined to a collecting riser I3, along with similar conduits, such as conduits I2A, I23, and I2C, partially shown in Fig. 1. Each such initial gathering conduit collects gas escaping from one or more retort-condenser combinations, as desired or convenient. The weight of riser I3, and of the gathering conduits connected to it, may be supported, at least in part, by a bracket I9 on which the riser rests. This riser I 3, along with other risers, not shown, lead to a main exhaust conduit I4. The gas removed from a plurality of individual retort-condenser combinations, and contalning small, suspended, metal-comprising particles, passes through conduit I4 to a duct filter I5, wherein the suspended metal-comprising particles are removed. These are recovered, as desired, through conduit 35. This removal may be effected by suitable use of conventional filtering means, such as filter bags, cyclone separators, electrical precipitators, or suitable combinations thereof, such equipment being well known to those skilled in the art of recovering suspended particles from gas. Gas from which such suspended particles have been removed is discharged from the filter I5 through conduit I6 by compressor or blower II. Such gas may, if desired, be discharged. However the gas leaving the condensers contains substantial amounts of carbon monoxide, a combustible gas. The gas passing through the exhaust system is a mixture of this escaping gas and air, and will contain this carbon monoxide if combustion is not allowed to take place at the condenser vents. This gas, passing through conduit I8, may be passed to the furnace, not shown, as at least a portion of the fuel-air mixture used for combustion and heating of the retorts. In this way fuel value of the carbon monoxide is utilized, as well as recovery of metal dust in the escaping gas. Operation in this manner, i. e. passing gas from conduit I8 to the combustion system which heats the retorts, is a preferred process embodiment of my present invention.

The cover II fits firmly against the end of condenser ID, as shown, being so suspended as to be held firmly by its own weight. Attached on each side of this cover I I are pivotal means, such as the projecting pins shown, having their axes on a common horizontal line which is located between the top and the center of gravity of cover II. Arms 2| and 2| connect and hold the cover II to the exhaust conduit. This is done by having them pivotally connected to bands 22 and 22, respectively, which in turn are secured to conduit I 2, as shown. The position of the axes of the latter pivotal connections is above, and back of, the end of the condenser III. The more this pivotal connection is back of the end of the condenser I0 the greater will the weight of the cover II cause it to press against the end of the condenser. At the front of hood 20 may be a small lip 25 in which the bottom of cover II may rest When the cover is in a raised position.

Referring now more particularly to Figures 4 and 5, gathering exhaust conduit I2 is further back from the front end of condenser I0, and the vent hole 23' is back slightly from the end. The collecting hood 30 is connected to conduit I2 by a short arm 33. Arms 2I and 2 I are pivotally attached to a band 32, clamped around arm 33. This band 32 can be readily moved back and forth on arm 33 so that the cover I I will be in the best position to fit tightly even though various condensers may have somewhat different lengths. This embodiment also uses somewhat longer arms 2I and 2I', resulting in a somewhat firmer fit of cover II against condenser I0. In many installations this is a preferred apparatus embodiment of my present invention.

Horizontal collecting exhaust conduits I2, I2A, etc., are preferably joined to riser I3 by a suitable flange, as shown, or other readily engageable and disengageable means. Likewise, riser I3 is similarily joined to main conduit I4'. When servicing the condensers, or the retorts, not shown, to which they are connected, this exhausting equipment may be an obstruction or hindrance, and it will be desired to disengage riser I3, and associated equipment, from conduit l4 and set it aside at such a time. The embodiments shown have the advantage that they can be readily so handled. At times riser 13 may be left in place and only conduits I2, 12A, etc., and associated equipment, so removed.

In any of these embodiments it is preferred that the hood, such as hood 20 or hood 30, does not fit so tightl or snugly against condenser 10 that contents of the condenser, or of the retort connected to it, are undesirably sucked into the exhaust system. Thus, it is desired to collect, without wastage, gas normally leaving the condenser but too much suction applied at the vent hole will cause disruption of the reacting mixture in the retort, with possible eruption of some of this material into the condenser. By properly spacing the hood away from condenser ill, and controlling the suction caused by exhaust fan ll, collection of the escaping gas, with some air, without the undesired effects discussed, can be readily obtained. Brief trials, conducted in the light of the teachings and discussion presented herein, will result in satisfactorily collecting the gas with any specific equipment. When the gas passing through conduit 18 is passed to the furnace, carbon monoxide so collected will burn as fuel and accompanying entrained air will serve as combustion air, or at least a substantial portion thereof, for combustion of this carbon monoxide and of other fuel burned in the furnace. Such air will also have the advantage of being at an appreciably higher temperature than combustion air drawn directly from the atmosphere.

The body of cover I I may be composed of molded ceramic material, or fire clay, or the like material, which is suitably resistant to high temperature, corrosion, and erosion. It may be made of a disc of such material surrounded by a band of steel to which the pivotal supports for arms 2| and 2 I are attached, or may be made by filling a dish shaped depression in a metal cover with such resistant material, or in any other suitable manner.

As previously mentioned, the drawings are diagrammatic. Various modifications of my invention, both of the apparatus and of the process embodiments, may be used, in the light of the present disclosure and teachings, by one skilled in the art without departing from the scope thereof, and without departing from the scope of the claims.

I claim:

1. In a device for smelting, the improved combination which comprises a main gas-exhaust conduit, means associated therewith for recovering dust entrained in gas passing therethrough, at least one exhaust riser associated with said main conduit, a plurality of horizontal gathering exhaust conduits connected with each said riser, at least one arm extending from each said gathering conduit, a gas-gathering hood at the end of each said arm, a fiat member adapted to serve as a cover for a condenser positioned beneath said hood, means adjustably and pivotally attaching each said flat member to the corresponding arm, each said flat member being individually movable to cover and uncover the outer end of a condenser suspended beneath said hood, and connecting means joining said riser and said main conduit whereby said riser and hereinbefore recited associated items can be readily removed from and reconnected to said main conduit as a unit.

2. An improved apparatus combination for smelting zinc, which comprises a horizontal condenser for condensing and collecting liquid zinc, a readily removable cover for the mouth of said condenser normally pressing against said condenser, a vent for discharging gas from said condenser, an exhaust conduit for transporting gas vented from said condenser, an individual hood covering said vent and connected with said exhaust conduit, said hood being disposed over and spaced from said vent to collect gas only from its corresponding vent together with some air, a lip at the front of said hood in which said cover may rest when in a raised position, and link means attaching said cover to said hood and cooperating therewith to hold said cover firmly against the mouth of said condenser and to hold said cover resting in said lip when said cover is raised from said condenser mouth.

FOREST C. BARBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,053,592 Gordon Feb. 18, 1913 1,573,013 Ogg Feb. 16, 1926 1,998,456 Hanson et al Apr. 23, 1935 2,191,066 Barber Feb. 20, 1940 2,206,150 Barber July 2, 1940 2,287,038 Janes June 23, 1942 2,383,209 Newkirk et a1 Aug. 21, 1945 

